Electronic Properties of Nitrogen-/Boron-Doped Graphene Nanoribbons With Armchair Edges

Calculation of electronic structures has been performed for graphene nanoribbons with eight-armchair edges containing nitrogen or boron substitutional impurity by using ab initio density functional theory. It is found that the electronic structures of the doped graphene nanoribbon are different from those of doped carbon nanotubes. The impurity levels are autoionized, so that the relevant charge carriers occupy the conduction or valence bands. The donor and acceptor levels are derived mainly from the lowest unoccupied orbital and highest occupied orbital of pristine graphene nanoribbon, respectively. N introduces an impurity level above the donor level, while an impurity level introduced by B is below the acceptor level. The doped graphene nanoribbons with armchair edges are inactive compared to the doped carbon nanotubes around the impurity site, which may indicate that the doped graphene nanoribbons with armchair edges could be more stable than the doped carbon nanotubes at the ambient.